This application claims the benefit of Korean Application No. 99-45847, filed Oct. 21, 1999, in the Korean Patent Office, the disclosure of which is incorporated herein by reference.
1. Field of the Invention
The present invention relates to an optical pickup assembly, and more particularly, to an optical pickup assembly having an improved structure for tilt control of an objective lens.
2. Description of the Related Art
In general, a disk player such as a CDP (compact disk player) or a DVDP (digital versatile disk player) which records information on or reproduces information from a disk includes an optical pickup assembly for recording and reproducing by emitting light to a disk and receiving light reflected therefrom while moving across the disk. The optical pickup assembly is usually provided with a controlling means for driving a bobbin at which an optical system including an objective lens is mounted in a focusing direction and a tracking direction, to perform focusing and tracking control so that light passing through the objective lens can be focused at a precise position on the disk. Recently, an optical pickup assembly which can perform tilt control in addition to focusing and tracking control is required. With tilt control, when a disk is inclined, the optical pickup assembly can be tilted corresponding to the inclination of the disk so that light is incident on the disk parallel to the normal.
FIG. 1 shows an optical pickup assembly having a conventional tilt control mechanism. As shown in the drawing, in the conventional tilt control mechanism, an optical pickup assembly including an objective lens 11 is installed as a whole at a pivot shaft 21 of a base 20 to be capable of pivoting. A degree of inclination of a disk 1 is measured by sensors 12 and 13 and then a tilt motor 30 is driven to tilt the entire optical pickup assembly 10 by a corresponding angle. Reference numeral 40 denotes a feeding motor for reciprocating the base 20 across the disk 1. However, in the tilt control mechanism having the above structure, since the optical pickup assembly 10 is installed to pivot as a whole, and the tilt motor 30 is additionally installed outside the optical pickup assembly 10, the overall system is large and complicated, which is contrary to the current trend of making systems light and small. Thus, an optical pickup assembly having a light and small structure with which tilt control can be stably performed is required.
To solve the above problems, it is an object of the present invention to provide an optical pickup assembly with a simple structure which can stably perform tilt control.
Additional objects and advantages of the invention will be set forth in part in the description which follows, and, in part, will be obvious from the description, or may be learned by practice of the invention.
Accordingly, to achieve the above and other objects, there is provided an optical pickup assembly which includes a bobbin at which an objective lens is mounted. An elastic support member supports the bobbin to move elastically with respect to a holder installed at a base. A focus coil and a tracking coil are installed at the bobbin and form a conducting path to drive the objective lens in a focusing direction and a tracking direction. Tilt coils are installed at one side of the bobbin and form a conductive path for driving a tilt of the objective lens. A first magnet and a first yoke generate an electromagnetic force to drive the objective lens together with the current carrying focus coil and tracking coil. A second magnet and a second yoke generate an electromagnetic force to driving the objective lens together with the current carrying tilt coils. A position detecting sensor measures relative inclination of the objective lens with respect to a disk, and a balance member coupled to the bobbin balances the weight of the tilt coils by applying weight corresponding to the weight of the tilt coils at positions symmetrically opposite to the positions of the tilt coils.